Fuelling Through the Heat

Irish sportive and audax season rarely coincides with genuine heat stress, but this summer has been the exception. With Met Éireann confirming another spell of high temperatures this week — highs of 27–29°C forecast in the midlands and east, on top of an already hot, dry summer and a nationwide hosepipe ban — riders lining up for an event this weekend need to rethink their usual fuelling plan. Irish cyclists simply haven’t built up the heat acclimatisation that riders in warmer climates take for granted, which makes event-day nutrition and hydration strategy more important than ever.

The Night Before and Breakfast

Start hydrating well before the start line, not on it. Aim for pale straw-coloured urine the evening before; this means you’re well hydrated. Have a carbohydrate-rich dinner — pasta, rice, or potatoes — to top up glycogen stores. On the morning of the event, eat a familiar, carb-heavy breakfast 2–3 hours before rolling out (porridge with banana and honey is a reliable option), paired with 500ml of fluid. In heat, consider adding a pinch of salt or an electrolyte tablet to your pre-ride drink to boost sodium retention.

Hydration During the Ride

In normal Irish conditions, one 750ml bottle per hour is often plenty. In the heat, sweat rates climb sharply and that’s no longer enough. Plan for 750ml–1L per hour, alternating plain water with an electrolyte drink containing 500–700mg of sodium per litre. Sodium losses matter more than people assume — cramping and the “washed out” feeling late in a ride are frequently signs of salt depletion rather than simple dehydration. If your event has feed stations, use every one of them to refill, even if you don’t feel thirsty yet: thirst lags behind actual fluid need, especially once you’re several hours in.

A useful practical check: weigh yourself before and after a training ride in similar heat. Losing more than 2% of body weight in sweat is linked to measurable drops in performance, so use that figure to calibrate how much you personally need to drink per hour.

Fuelling on the Bike

Aim for 60–90g of carbohydrate per hour on rides over 90 minutes — a mix of glucose and fructose (found in most commercial gels and drink mixes) is absorbed faster than glucose alone. Solid food like a banana, a malt loaf slice, or a jam sandwich works well earlier in a long event; switch to gels and easily digestible carbs in the final hours, especially in heat, when blood flow is diverted to the skin and digestion slows.

Heat-Specific Adjustments

Start slightly slower than planned, seek shade at feed stops, and consider pre-cooling with a cold drink or ice in your jersey pockets before the start on really hot days. Watch for early signs of heat stress — dizziness, chills despite the heat, or a stop in sweating — and slow down or stop immediately if they appear.

Ireland’s heat is unusual this year, but the fix is straightforward: drink more than feels natural, salt your fluids, and fuel steadily. Your legs will thank you by kilometre 100.